List merging using names and varnames-CodePudding

I would like to perform a left_join between elements of two lists, conditional on the fact that the lista share the same name (I cannot use a simple left_joinon the databases for memory reasons).

set.seed(0)
db_m1 <- data.frame(
  y=rep(1,20),
  id=sort(rep(paste0("id_",c(letters[1:4])),5)),
  m1=rep(c(100,200),10),
  x1=sample(LETTERS, 20, TRUE),
  x2=sample(LETTERS, 20, TRUE)) %>% 
  split(f=list(.$y,.$m1))

set.seed(0) 
db_m2 <- data.frame(y=rep(1,20),
                    m1=sample(seq(100,500,100),20,TRUE),
                    m2=sample(c(6:10),20,TRUE)) %>% 
  split(f=list(.$y,.$m1))

Desiderata:

$`1.100`
   y   id  m1 x1 x2 m2
1  1 id_a 100  N  O 10
2  1 id_a 100  N  O  7
(...)

$`1.200`
    y   id  m1 x1 x2 m2
7   1 id_a 200  Y  U  6
8   1 id_a 200  Y  U  9
(...)

CodePudding user response：

keys <- unique(c(names(candidates_0_s)))
setNames(lapply(keys, function(key){
  result <- left_join(candidates_0_s[[key]],allies_0_s[[key]])
  return(result)}
),keys)

CodePudding user response：

same idea, but in base R and working with your example:

common <- intersect(names(db_m1), names(db_m2))
merge_items <- function(item) merge(db_m1[[item]], db_m2[[item]], all.x = TRUE)
res <- lapply(common, merge_items)

output:

> lapply(res, head)
[[1]]
  y  m1   id x1 x2 m2
1 1 100 id_a  N  O 10
2 1 100 id_a  N  O  7
3 1 100 id_a  N  O  7
4 1 100 id_a  N  O  9
5 1 100 id_a  N  O  9
6 1 100 id_a  N  O  6

[[2]]
  y  m1   id x1 x2 m2
1 1 200 id_a  Y  U  6
2 1 200 id_a  Y  U  9
3 1 200 id_a  Y  U  9
4 1 200 id_a  Y  U  7
5 1 200 id_a  G  I  6
6 1 200 id_a  G  I  9